1. Field of the Invention
The invention relates to a bus system.
1. Background Information
Electronics is being used to an increasing extent in all fields of modern technology. This also applies in particular to modern automobile technology with a constant increase in electrical components, motors and assemblies as well as electronic systems which have to be actuated at least partially by means of switches and control elements. This applies for example to the body system with lights, central locking, door securing elements, window lifters, rear view mirror adjustment, heating and air-conditioning system, adjustment of seat belts and seats etc. Since the switches or control elements have to be arranged in the region of the user and thus usually at a distance from the respective electronic system, extensive wiring of the respective switches and control elements is required. Often more than 100 cables and plug-in connections for connecting such switches and control elements have to be accommodated in the region of the dashboard of a modern motor vehicle alone. An additional factor is that modern vehicle safety systems, such as for example brake monitoring, anti-lock system, traction slip control etc., and electronic engine and transmission control require complex sensor systems which also have to be wired up. Thus, such conventional wiring has developed to an extent which is hardly manageable any more.
Due to this wiring which is constantly becoming more extensive, the problems which occur as a result of electromagnetic interference radiations of the conventional wiring lines and vice versa as a result of interference signals being picked up in the wiring lines are constantly increasing.
In order to remedy this, it has become known in vehicle manufacture to realize a network of electronic control devices by means of a bus system, as a result of which as many electronic control systems or control devices as desired can be connected together in the motor vehicle by means of a common bus and can exchange data. A bus system of this kind is for example the known CAN bus (CAN=Controller Area Network). It is disadvantageous here that this solution involves a very complex and cost-intensive connection of the control systems and devices to the bus system which is completely over-dimensioned for the majority of control elements located in the motor vehicle. In addition, special, and thus expensive, control devices for this bus system are required.
It is also known from computer technology to connect a bus to a superordinate main bus. Thus, the German Offenlegungsschrift 37 43 847 shows the connection of a plurality of sensor modules, serving to detect measurement variables, to a measurement bus, the bus being a parallel microprocessor bus, the sensor modules being connected to a central computer and being addressed by the central computer by means of an address. A plurality of these central computers communicate in turn with a superordinate host computer via its own main bus, by which means a flexible process measurement data detection and processing system is to be provided.
However, it is disadvantageous that this is also a complex system which is specially adapted to the functions of the process data processing. A system of this kind is also overdimensioned for the demands made on the majority of control elements in the motor vehicle and cannot be used cost effectively. In particular, the system is not suitable for connecting into a bus system sensors, actuators and mechanical switches which are organized in binary fashion.